Accurately estimate the weight of blind flanges based on their dimensions and material density. Essential for project planning, material estimation, and cost control in piping and structural engineering.
Blind Flange Weight Calculator
Enter NPS (e.g., 6) or OD (e.g., 168.3 mm). For NPS, the calculator will use standard OD.
Enter the flange thickness in millimeters (mm).
Enter the bore diameter in millimeters (mm). Leave blank if not applicable or full face.
Steel (Carbon Steel/Stainless Steel) – 7.85 g/cm³
Aluminum – 7.00 g/cm³
Cast Iron – 8.60 g/cm³
Titanium – 10.20 g/cm³
Gold – 19.30 g/cm³
Lead – 11.34 g/cm³
Magnesium – 2.70 g/cm³
Nickel – 8.90 g/cm³
Platinum – 21.45 g/cm³
Wrought Iron – 7.80 g/cm³
Custom
Select material or enter custom density.
Enter the density for your specific material.
Calculation Results
— kg
Volume: — cm³
Weight (kg): — kg
Weight (lbs): — lbs
The blind flange weight is calculated by determining its volume and multiplying it by the material's density. The volume of a blind flange is approximated as a solid cylinder with a central cylindrical hole removed (if a bore diameter is provided).
Weight vs. Diameter for a Standard Thickness
What is a Blind Flange Weight Calculator?
A Blind Flange Weight Calculator is a specialized engineering tool designed to accurately determine the mass of a blind flange. Blind flanges are crucial components in piping systems, acting as solid discs that close off the end of a pipe or vessel opening. They differ from other flange types by lacking a central opening. This calculator uses input parameters such as the flange's dimensions (outside diameter, thickness, bore diameter if applicable) and the material's density to compute its total weight. Understanding the precise weight of a blind flange is vital for several reasons, including material handling, structural support design, transportation logistics, and overall project costing.
Who Should Use This Calculator?
This blind flange weight calculator is an indispensable tool for a wide range of professionals in the industrial sector:
Piping Engineers: To ensure accurate material take-offs and to design appropriate support structures.
Procurement Specialists: To get precise weight estimates for quoting and purchasing.
Fabricators and Manufacturers: To plan production and manage inventory.
Safety Officers: For proper planning of lifting and handling operations.
Project Managers: To control budgets and timelines by accurately estimating material costs and logistical needs.
Students and Educators: To learn about flange specifications and engineering calculations.
Common Misconceptions
A common misconception is that all flanges of the same nominal pipe size (NPS) weigh the same. In reality, variations in manufacturing standards (like ASME, DIN), flange ratings (pressure classes), material grades, and even minor dimensional differences can significantly affect the final weight of a blind flange. Another misconception is that the bore diameter is always relevant; for many blind flange applications, the entire face is solid, meaning there is no bore diameter to consider.
Blind Flange Weight Formula and Mathematical Explanation
The calculation of a blind flange's weight is fundamentally based on its volume and the density of the material it's made from. The standard formula is:
Weight = Volume × Density
Volume Calculation
The volume of a blind flange can be visualized as a solid disc with a smaller cylindrical void in the center (if a bore is present). The formula for its volume ($V$) in cubic centimeters (cm³) is:
$R_{outer}$ is the outer radius of the flange (half of the outer diameter).
$R_{inner}$ is the inner radius of the flange (half of the bore diameter). If no bore diameter is specified, $R_{inner}$ is considered 0, simplifying the calculation to a solid cylinder.
$Thickness$ is the thickness of the flange.
All dimensions must be in consistent units, typically millimeters (mm) for flange dimensions, which then need to be converted to centimeters (cm) for density calculations in g/cm³.
Unit Conversions
1 cm = 10 mm
1 mm = 0.1 cm
1 cm³ = 1000 mm³
Density and Weight
Density ($\rho$) is typically given in grams per cubic centimeter (g/cm³). Once the volume ($V$) is calculated in cm³, the weight in grams (g) is:
Weight (g) = $V_{cm^3} \times \rho_{g/cm^3}$
To convert grams to kilograms (kg), divide by 1000:
Weight (kg) = Weight (g) / 1000
To convert kilograms to pounds (lbs), multiply by approximately 2.20462:
Weight (lbs) = Weight (kg) × 2.20462
Standard Dimensions for NPS (Nominal Pipe Size)
For calculations involving NPS, standard outside diameters (OD) are used. The calculator approximates these based on common standards (e.g., ASME B16.5). For example:
NPS 6″ typically corresponds to an OD of 168.3 mm.
NPS 8″ typically corresponds to an OD of 219.1 mm.
NPS 10″ typically corresponds to an OD of 273.0 mm.
These values are approximate and can vary slightly depending on the specific standard and flange rating.
Variables Table
Blind Flange Weight Calculator Variables
Variable
Meaning
Unit
Typical Range / Notes
NPS / OD
Nominal Pipe Size or Outside Diameter of the flange
inches (for NPS), mm (for OD)
NPS: 1/2″ to 24″+; OD: Varies significantly based on NPS and pressure class.
Thickness
The axial thickness of the blind flange.
mm
Depends on pressure rating and NPS; typically 5 mm to 50+ mm.
Bore Diameter
The diameter of the central opening (if any). A value of 0 or blank indicates a solid face.
mm
Depends on the inner diameter of the pipe it seals.
Example 1: Standard Steel Blind Flange for an 8-inch Pipe
A project requires a standard blind flange to seal the end of an 8-inch Schedule 40 carbon steel pipe. The flange has a standard thickness for this size and pressure class, and it's a full face blind flange (no bore). The material is specified as ASTM A105 carbon steel.
Input: Nominal Pipe Size (NPS): 8 inches
Input: Flange Thickness: 22.25 mm (Standard for 8″ Class 150 RF)
Input: Bore Diameter: (Leave blank – full face)
Input: Material Density: 7.85 g/cm³ (Carbon Steel)
Calculation Steps:
Determine OD: For NPS 8″, standard OD is approx. 219.1 mm.
Calculate Radii: $R_{outer}$ = 219.1 mm / 2 = 109.55 mm. $R_{inner}$ = 0 mm (since it's a full face).
Convert Dimensions to cm: Thickness = 22.25 mm = 2.225 cm. $R_{outer}$ = 109.55 mm = 10.955 cm.
Convert to kg: Weight = 65653.3 g / 1000 ≈ 65.65 kg.
Convert to lbs: Weight = 65.65 kg × 2.20462 ≈ 144.7 lbs.
Result Interpretation: The 8-inch blind flange weighs approximately 65.65 kg (144.7 lbs). This weight is critical for specifying lifting equipment and ensuring the structural integrity of the piping system supports.
Example 2: Smaller Stainless Steel Blind Flange with a Bore
A smaller stainless steel blind flange is needed for a chemical processing line. It's for a 4-inch pipe, has a specific thickness, and requires a bore to allow some fluid passage before final connection.
Input: Nominal Pipe Size (NPS): 4 inches
Input: Flange Thickness: 16.0 mm
Input: Bore Diameter: 90.0 mm
Input: Material Density: 7.85 g/cm³ (Stainless Steel)
Calculation Steps:
Determine OD: For NPS 4″, standard OD is approx. 114.3 mm.
Calculate Radii: $R_{outer}$ = 114.3 mm / 2 = 57.15 mm. $R_{inner}$ = 90.0 mm / 2 = 45.0 mm.
Convert Dimensions to cm: Thickness = 16.0 mm = 1.6 cm. $R_{outer}$ = 57.15 mm = 5.715 cm. $R_{inner}$ = 45.0 mm = 4.5 cm.
Convert to lbs: Weight = 0.18 kg × 2.20462 ≈ 0.40 lbs.
Result Interpretation: This smaller stainless steel blind flange with a bore weighs only about 0.18 kg (0.40 lbs). This is significantly less than a full-face flange of the same OD and thickness, highlighting the impact of the bore diameter on the overall weight and material usage. This is crucial for applications where weight is a critical factor.
How to Use This Blind Flange Weight Calculator
Using this blind flange weight calculator is straightforward. Follow these simple steps to get your weight estimate:
Step-by-Step Instructions
Input Flange Dimensions:
Nominal Pipe Size (NPS) or Outside Diameter (OD): Enter the NPS (e.g., "6" for a 6-inch pipe size) or the exact Outside Diameter (OD) of the flange in millimeters (e.g., "168.3"). If you enter an NPS, the calculator will use a standard OD value for that size.
Flange Thickness: Enter the thickness of the blind flange in millimeters (mm).
Bore Diameter (Optional): If the blind flange has a central bore, enter its diameter in millimeters (mm). If it's a solid, full-face flange, leave this field blank.
Select Material Density:
Choose your flange material from the dropdown list (e.g., Carbon Steel, Stainless Steel). The calculator pre-fills the corresponding density in g/cm³.
If your material isn't listed, select "Custom" and enter the exact density value in g/cm³ in the "Custom Density" field that appears.
Calculate: Click the "Calculate Weight" button.
How to Read the Results
Once you click "Calculate Weight", the calculator will display:
Primary Highlighted Result (Weight): This is the main output, showing the estimated weight of the blind flange in kilograms (kg). It's presented prominently for quick reference.
Intermediate Values:
Volume: The calculated volume of the flange material in cubic centimeters (cm³).
Weight (kg): The weight in kilograms, displayed again for clarity.
Weight (lbs): The equivalent weight in pounds (lbs).
Formula Explanation: A brief description of the calculation method used.
Chart: A visual representation showing how the weight changes with the outer diameter for a fixed thickness, allowing for quick comparisons.
Table: A detailed breakdown of standard dimensions and material properties used in flange calculations.
Decision-Making Guidance
The calculated weight is crucial for several engineering and logistical decisions:
Material Procurement: Provides accurate data for purchasing and inventory management.
Handling and Installation: Helps in planning the necessary lifting equipment (cranes, hoists) and manpower for safe installation.
Structural Design: Essential input for engineers designing supports, foundations, or structural elements that will bear the weight of the piping system.
Transportation: Aids in calculating shipping costs and ensuring compliance with transport regulations.
Cost Estimation: A significant factor in the overall cost of a piping project.
Key Factors That Affect Blind Flange Weight Results
Several factors influence the calculated weight of a blind flange. Understanding these is key to interpreting the results accurately:
Outer Diameter (OD) and Nominal Pipe Size (NPS):
This is the most significant factor. A larger diameter directly increases the flange's surface area and thus its volume and weight. The relationship is quadratic ($OD^2$), meaning doubling the diameter quadruples the weight, assuming thickness remains constant. This is why selecting the correct NPS or OD is paramount.
Flange Thickness:
Thickness is directly proportional to weight. A thicker flange has a larger volume and therefore weighs more. Flange thickness is determined by the pressure rating (Class) and the NPS, with higher pressure classes requiring thicker flanges. This factor is critical for structural integrity under pressure.
Bore Diameter:
The presence and size of a bore diameter directly reduce the flange's volume and weight. A full-face blind flange (no bore) will be heavier than a similar-sized flange with a significant bore. The bore is typically matched to the internal diameter of the pipe it is sealing.
Material Density:
Different materials have different densities. For example, a titanium blind flange will be significantly lighter than a steel one of the same dimensions (Titanium ~4.5 g/cm³ vs. Steel ~7.85 g/cm³). Similarly, aluminum flanges are much lighter than steel. Choosing the correct density for the specified material is essential for accurate weight calculations.
Manufacturing Tolerances:
Real-world manufacturing involves slight variations. Flange dimensions (OD, thickness, bore) might deviate slightly from nominal specifications within acceptable tolerance limits. These small variations can lead to minor differences in actual weight compared to calculated weight. This calculator uses standard or specified dimensions, assuming them to be accurate.
Flange Standards and Pressure Ratings (Class):
Different standards (e.g., ASME B16.5, DIN EN 1092-1) and pressure ratings (e.g., Class 150, 300, PN16) dictate specific dimensional requirements, including OD, thickness, and bolt hole patterns. A higher pressure rating generally implies a thicker, heavier flange for a given NPS.
Coating or Cladding:
While not typically included in basic weight calculations, some flanges might have coatings (e.g., galvanizing) or be made of clad materials. These add a small amount of weight not accounted for by the base material density.
Frequently Asked Questions (FAQ)
What is the difference between NPS and OD for a blind flange?
NPS (Nominal Pipe Size) is a standardized designation for pipe and fittings, referring to the approximate inside diameter. The Outside Diameter (OD) is the actual physical measurement of the pipe's outer surface. For flanges, the OD is the critical dimension that determines the flange's overall size and weight. While NPS is used for convenience (e.g., "8-inch flange"), the calculator often needs the actual OD, which varies slightly by standard and pressure class. For NPS values, the calculator uses common OD equivalents.
How accurate is this blind flange weight calculator?
This calculator provides a highly accurate estimate based on standard engineering formulas and typical material densities. However, the accuracy depends on the precision of the input values (dimensions, density) and adherence to standard manufacturing tolerances. For critical applications requiring exact weights, always consult manufacturer specifications or perform direct measurements.
Can I use this calculator for flanges not made of steel?
Yes, absolutely. The calculator allows you to select from various common materials or enter a custom density. Just ensure you have the correct density value (in g/cm³) for your specific material, whether it's stainless steel, aluminum, titanium, or another alloy.
What does "full face" mean for a blind flange?
"Full face" indicates that the blind flange covers the entire face of the mating flange, including the raised face (RF) or ring type joint (RTJ) area. Crucially, it means there is no central bore (opening) through the flange. When inputting dimensions, you would leave the bore diameter blank or enter 0 for a full-face blind flange.
Why is the weight of a blind flange important?
The weight is crucial for material handling (lifting equipment), structural support design (ensuring supports can bear the load), transportation logistics (shipping costs and regulations), and accurate project cost estimation. It's a fundamental parameter in piping system design and implementation.
Does the calculator account for bolt holes?
The standard volume calculation for a blind flange (a solid disc minus a central bore) does not explicitly subtract the volume of the bolt holes. Bolt holes are relatively small compared to the overall flange volume, and their impact on the total weight is usually negligible for most practical purposes. This calculator focuses on the primary mass calculation based on the main dimensions.
What is the typical density of stainless steel for flanges?
The typical density for both carbon steel and most common stainless steel alloys (like 304 and 316) used in flanges is approximately 7.85 grams per cubic centimeter (g/cm³). You can select "Steel (Carbon Steel/Stainless Steel)" from the dropdown, or input 7.85 manually if using a custom option.
Can I calculate the weight for different pressure classes?
Yes, indirectly. Different pressure classes (e.g., Class 150, Class 300) have different standard thicknesses for a given NPS. You should input the specific thickness associated with the pressure class you are using. For example, an 8-inch Class 300 blind flange will be thicker and heavier than an 8-inch Class 150 blind flange.
Direct link to the input fields for quick adjustments and calculations.
var standardODs = {
"1/2": 21.3, "3/4": 26.7, "1": 33.4, "1 1/4": 42.2, "1 1/2": 48.3, "2": 60.3,
"2 1/2": 73.0, "3": 88.9, "4": 114.3, "5": 141.3, "6": 168.3, "8": 219.1,
"10": 273.0, "12": 323.9, "14": 355.6, "16": 406.4, "18": 457.2, "20": 508.0,
"22": 559.0, "24": 610.0
};
function getODFromNPS(npsString) {
if (!npsString) return null;
npsString = npsString.trim();
if (standardODs[npsString]) {
return standardODs[npsString];
}
// Try to handle float inputs like "6.0"
for (var key in standardODs) {
if (parseFloat(key) === parseFloat(npsString)) {
return standardODs[key];
}
}
return null;
}
function validateInput(id, errorId, min, max, allowEmpty, isFloat) {
var input = document.getElementById(id);
var errorSpan = document.getElementById(errorId);
var value = input.value.trim();
var numValue;
if (allowEmpty && value === "") {
errorSpan.textContent = "";
errorSpan.style.display = 'none';
return true;
}
if (value === "") {
errorSpan.textContent = "This field is required.";
errorSpan.style.display = 'block';
return false;
}
if (isFloat) {
numValue = parseFloat(value);
if (isNaN(numValue)) {
errorSpan.textContent = "Please enter a valid number.";
errorSpan.style.display = 'block';
return false;
}
} else {
numValue = parseInt(value);
if (isNaN(numValue)) {
errorSpan.textContent = "Please enter a whole number.";
errorSpan.style.display = 'block';
return false;
}
}
if (min !== null && numValue max) {
errorSpan.textContent = "Value is too high.";
errorSpan.style.display = 'block';
return false;
}
errorSpan.textContent = "";
errorSpan.style.display = 'none';
return true;
}
function calculateFlangeWeight() {
var diameterInput = document.getElementById('diameter');
var thicknessInput = document.getElementById('thickness');
var boreDiameterInput = document.getElementById('boreDiameter');
var materialDensitySelect = document.getElementById('materialDensity');
var customDensityInput = document.getElementById('customDensityValue');
var isValid = true;
var diameterValue = diameterInput.value.trim();
var effectiveOD = null;
var diameterUnit = "mm"; // Assume mm for OD input
if (diameterValue === "") {
isValid = validateInput('diameter', 'diameterError', 0, null, false) && isValid;
} else {
var npsValue = getODFromNPS(diameterValue);
if (npsValue !== null) {
effectiveOD = npsValue;
diameterUnit = "mm (from NPS)";
} else {
// Assume it's already an OD in mm
effectiveOD = parseFloat(diameterValue);
if (isNaN(effectiveOD) || effectiveOD outerRadiusMM) {
document.getElementById('boreDiameterError').textContent = "Bore diameter cannot be larger than OD.";
document.getElementById('boreDiameterError').style.display = 'block';
isValid = false;
// Clear results if validation fails
document.getElementById('primaryResult').textContent = "– kg";
document.getElementById('volumeResult').textContent = "– cm³";
document.getElementById('weightResultKg').textContent = "– kg";
document.getElementById('weightResultLbs').textContent = "– lbs";
updateChart([], []); // Clear chart
return;
} else {
document.getElementById('boreDiameterError').textContent = "";
document.getElementById('boreDiameterError').style.display = 'none';
}
// Convert dimensions to CM for density calculation
var outerRadiusCM = outerRadiusMM / 10;
var innerRadiusCM = innerRadiusMM / 10;
var thicknessCM = thicknessValue / 10;
// Calculate Volume in cm³
var volumeCM3 = Math.PI * (Math.pow(outerRadiusCM, 2) – Math.pow(innerRadiusCM, 2)) * thicknessCM;
volumeCM3 = Math.max(0, volumeCM3); // Ensure volume is not negative
// Calculate Weight in grams
var weightGrams = volumeCM3 * densityValue;
// Convert Weight to Kilograms and Pounds
var weightKg = weightGrams / 1000;
var weightLbs = weightKg * 2.20462;
// Display Results
document.getElementById('primaryResult').textContent = weightKg.toFixed(2) + " kg";
document.getElementById('volumeResult').textContent = volumeCM3.toFixed(2) + " cm³";
document.getElementById('weightResultKg').textContent = weightKg.toFixed(2) + " kg";
document.getElementById('weightResultLbs').textContent = weightLbs.toFixed(2) + " lbs";
// Prepare data for chart (e.g., showing weight for 5 different diameters with same thickness)
var chartData = [];
var baseThickness = parseFloat(thicknessInput.value); // Use input thickness
var diameters = [6, 8, 10, 12, 14]; // NPS for chart example
var chartDiametersMm = [];
var chartWeightsKg = [];
for (var i = 0; i currentOuterRadiusMM) {
currentInnerRadiusMM = 0; // Avoid negative volume if bore > OD for smaller NPS
}
var currentOuterRadiusCM = currentOuterRadiusMM / 10;
var currentInnerRadiusCM = currentInnerRadiusMM / 10;
var currentThicknessCM = baseThickness / 10;
var currentVolumeCM3 = Math.PI * (Math.pow(currentOuterRadiusCM, 2) – Math.pow(currentInnerRadiusCM, 2)) * currentThicknessCM;
currentVolumeCM3 = Math.max(0, currentVolumeCM3);
var currentWeightGrams = currentVolumeCM3 * densityValue;
var currentWeightKg = currentWeightGrams / 1000;
chartDiametersMm.push(currentOD);
chartWeightsKg.push(currentWeightKg);
}
}
updateChart(chartDiametersMm, chartWeightsKg, diameterUnit);
}
function resetCalculator() {
document.getElementById('diameter').value = "6"; // Default to NPS 6
document.getElementById('thickness').value = "19.05"; // Default to Class 150 thickness for NPS 6
document.getElementById('boreDiameter').value = "";
document.getElementById('materialDensity').value = "7.85";
document.getElementById('customDensityValue').value = "";
document.getElementById('customDensityGroup').style.display = 'none';
// Clear error messages
document.getElementById('diameterError').textContent = "";
document.getElementById('diameterError').style.display = 'none';
document.getElementById('thicknessError').textContent = "";
document.getElementById('thicknessError').style.display = 'none';
document.getElementById('boreDiameterError').textContent = "";
document.getElementById('boreDiameterError').style.display = 'none';
document.getElementById('customDensityValueError').textContent = "";
document.getElementById('customDensityValueError').style.display = 'none';
calculateFlangeWeight(); // Recalculate with defaults
}
function copyResults() {
var primaryResult = document.getElementById('primaryResult').textContent;
var volumeResult = document.getElementById('volumeResult').textContent;
var weightKgResult = document.getElementById('weightResultKg').textContent;
var weightLbsResult = document.getElementById('weightResultLbs').textContent;
var diameter = document.getElementById('diameter').value;
var thickness = document.getElementById('thickness').value;
var boreDiameter = document.getElementById('boreDiameter').value;
var materialDensitySelect = document.getElementById('materialDensity');
var selectedMaterial = materialDensitySelect.options[materialDensitySelect.selectedIndex].text;
var customDensity = document.getElementById('customDensityValue').value;
var clipboardText = "Blind Flange Weight Calculation Results:\n\n";
clipboardText += "Primary Result: " + primaryResult + "\n\n";
clipboardText += "Intermediate Values:\n";
clipboardText += "- Volume: " + volumeResult + "\n";
clipboardText += "- Weight (kg): " + weightKgResult + "\n";
clipboardText += "- Weight (lbs): " + weightLbsResult + "\n\n";
clipboardText += "Assumptions/Inputs:\n";
clipboardText += "- Diameter/NPS: " + diameter + "\n";
clipboardText += "- Thickness: " + thickness + " mm\n";
clipboardText += "- Bore Diameter: " + (boreDiameter === "" ? "N/A (Full Face)" : boreDiameter + " mm") + "\n";
if (materialDensitySelect.value === "custom") {
clipboardText += "- Material Density: " + customDensity + " g/cm³ (Custom)\n";
} else {
clipboardText += "- Material: " + selectedMaterial + "\n";
}
navigator.clipboard.writeText(clipboardText).then(function() {
// Success feedback (optional)
var button = event.target;
var originalText = button.innerText;
button.innerText = "Copied!";
setTimeout(function() {
button.innerText = originalText;
}, 2000);
}, function() {
// Failure feedback (optional)
alert("Failed to copy results. Please copy manually.");
});
}
// Charting Logic
var myChart;
function updateChart(diametersMm, weightsKg, unit) {
var ctx = document.getElementById('weightChart').getContext('2d');
// Destroy previous chart instance if it exists
if (myChart) {
myChart.destroy();
}
var maxWeight = weightsKg.length > 0 ? Math.max(…weightsKg) : 10;
var yAxisMax = maxWeight * 1.2; // Add some buffer
myChart = new Chart(ctx, {
type: 'bar',
data: {
labels: diametersMm.map(function(d) { return d + " mm OD"; }),
datasets: [{
label: 'Weight (kg)',
data: weightsKg,
backgroundColor: 'rgba(0, 74, 153, 0.6)', // Primary color
borderColor: 'rgba(0, 74, 153, 1)',
borderWidth: 1
},
{
label: 'Target Diameter Weight',
data: diametersMm.map(function(d) {
if (d === parseFloat(document.getElementById('diameter').value.trim()) || getODFromNPS(document.getElementById('diameter').value.trim()) === d) {
return parseFloat(document.getElementById('weightResultKg').textContent.replace(" kg", ""));
}
return null; // Only show marker for the current input diameter
}),
type: 'scatter', // Use scatter for a single point marker
backgroundColor: 'rgba(40, 167, 69, 1)', // Success color
borderColor: 'rgba(40, 167, 69, 1)',
pointRadius: 8,
pointHoverRadius: 10,
showLine: false // Don't draw a line for scatter points
}]
},
options: {
responsive: true,
maintainAspectRatio: true, // Allow aspect ratio control
scales: {
y: {
beginAtZero: true,
title: {
display: true,
text: 'Weight (kg)'
},
max: yAxisMax
},
x: {
title: {
display: true,
text: 'Flange Outside Diameter (' + unit + ')'
}
}
},
plugins: {
legend: {
display: true,
position: 'top',
},
tooltip: {
callbacks: {
label: function(context) {
var label = context.dataset.label || ";
if (label) {
label += ': ';
}
if (context.parsed.y !== null) {
label += context.parsed.y.toFixed(2) + ' kg';
}
return label;
}
}
}
}
}
});
// Update legend
var legendHtml = 'Chart Legend:
';
legendHtml += '
Bar: Estimated weight for various diameters (at constant thickness)
';
legendHtml += '
Circle: Weight for your specified diameter
';
legendHtml += '
';
document.getElementById('chartLegend').innerHTML = legendHtml;
}
// Initial setup and event listeners
document.addEventListener('DOMContentLoaded', function() {
// Handle custom density visibility
var densitySelect = document.getElementById('materialDensity');
var customDensityGroup = document.getElementById('customDensityGroup');
var customDensityInput = document.getElementById('customDensityValue');
function toggleCustomDensity() {
if (densitySelect.value === 'custom') {
customDensityGroup.style.display = 'block';
validateInput('customDensityValue', 'customDensityValueError', 0.01, null, false); // Validate on show
} else {
customDensityGroup.style.display = 'none';
// Clear custom density value and error when hiding
customDensityInput.value = "";
document.getElementById('customDensityValueError').textContent = "";
document.getElementById('customDensityValueError').style.display = 'none';
}
}
densitySelect.addEventListener('change', toggleCustomDensity);
toggleCustomDensity(); // Initial check
// Trigger calculation on initial load with default values
calculateFlangeWeight();
// Add input event listeners for real-time updates (optional, but good UX)
document.getElementById('diameter').addEventListener('input', calculateFlangeWeight);
document.getElementById('thickness').addEventListener('input', calculateFlangeWeight);
document.getElementById('boreDiameter').addEventListener('input', calculateFlangeWeight);
document.getElementById('materialDensity').addEventListener('change', calculateFlangeWeight);
document.getElementById('customDensityValue').addEventListener('input', calculateFlangeWeight);
});
// Function to toggle FAQ answers
function toggleFaq(element) {
var faqItem = element.closest('.faq-item');
var content = faqItem.querySelector('p');
if (content.style.display === 'block') {
content.style.display = 'none';
faqItem.classList.remove('open');
} else {
content.style.display = 'block';
faqItem.classList.add('open');
}
}
// Add chart.js library dynamically or ensure it's loaded
// For this example, we assume chart.js is available globally or loaded externally.
// In a production setup, you'd include Chart.js via CDN or local file:
//